Access to the patient vascular system is necessary for a wide variety of purposes in medicine, most often related to the diagnosis or treatment of the heart or the vascular system. For example, angioplasty balloons, coronary stents and percutaneous stent grafts for abdominal aortic aneurysms are often delivered to the arterial system while vena cava filters are often delivered to the venous system.
Typically devices are introduced to the vascular system using either surgical cut down techniques or percutaneous introduction techniques in which an opening is created in the wall of a vessel, frequently the femoral artery, that runs relatively close to the surface of the body.
Smaller devices (6-8 Fr) are typically introduced percutaneously and closed using either manual compression or with a closure device. One of many closure devices designed specifically for small arteriotomy openings may be used. These devices include clips, staples, automated suturing mechanisms, plugs made from collagen or other biologic materials, fillers, glues and the like. These devices have the advantage of speeding up recovery, reducing costs and decreasing the length of hospitalization.
Recent improvements in minimally invasive transvascular device therapy offer less invasive approaches to many new, significant vascular and cardiovascular medical problems but also require larger access sites. Examples of new therapies that fall into this category include percutaneous aortic valve replacement, percutaneous mitral valve repair, abdominal aortic valve stent graft therapy and acute cardiac support with percutaneously placed pumps. Below 12 Fr percutaneous techniques are typically used. In the 12-16 Fr range, either cut down or percutaneous approaches may be used and above 16 Fr. a surgical cut down is almost always used.
Each of these approaches presents the physician and patient with numerous challenges. Surgical cutdowns often require coordinating schedules with a second physician trained in these techniques, typically a surgeon. They incur the additional time and cost associated with this additional procedure as well as causing additional physical pain to the patient. Moreover, cut down techniques can be quite disruptive to the tissue involved.
Larger holes can be made percutaneously using the standard Seldinger technique followed by multiple, progressively larger obdurators—but this approach often leads to high rates of hematoma and other access site complications. When the standard Seldinger technique is used for initial access, a first needle and guidewire are followed by progressively larger dilators until an opening of sufficient size is created. This method of penetration of the vessel is traumatic to both the tissue tract and the vessel wall. Advancement of the obdurator exerts axial force on tissue and may cause injury to this tissue. The round, progressively larger obdurators used to open the artery leave behind a large, ragged and highly variable vessel opening. Because the opening is ragged, getting edge to edge alignment and apposition is difficult and achieving hemostasis is challenging.
The closure of small holes in vessels is an area that has seen much innovation and the prior art is extensive. The need to open and close larger holes is only now emerging with the development and growth of new therapies. Few specific solutions have been developed to address these needs.
Large size openings preclude most small vessel closure solutions for numerous reasons. Approaches like glues and plugs typically do not provide the mechanical strength required to pull and keep opposing vessel edges together when the opening is large and the vessel is under pressure. Suture based approaches are challenged by ragged, poorly defined, hard to locate vessel edges which make getting good attachment of the suture to the tissue difficult and subsequent closure very hard.
U.S. Patent Publication No. 2008/0208213 to Benjamin, discloses a means for opening as well as closing a large hole in an artery but does not disclose a means for accessing the artery through the tissue. Also, it discloses a traditional surgical cutting tool and an initial cutting procedure that includes numerous steps, requires considerable manipulation through a small opening and consists of a high degree of complexity. Moreover, the tools described are unlike those typically used by interventionalists and not likely to offer the familiarity and ease of use required for adoption.
A tool kit providing for access to the target artery or vein, a subsequent means for opening the artery in a controlled way and creating an opening with smooth edges and a consistent, characteristic easy to close shape would be desirable. Moreover, a means to prospectively load the edges of the opening with sutures or another means of closure such that easy closure is assured—prior to advancing subsequent devices through the opening—would be desirable.
Numerous unmet needs exist in this area. It would be preferable to replace the surgical procedure required to open the artery with a minimally invasive procedure that could be done by the interventionalist rather than requiring a surgeon and an operating room. Additionally, it would be preferable to provide for a more predictable, less traumatized vessel opening as part of gaining initial access to the artery or vein. It would be preferable that a device or tool kit should provide for access in vessels up to 10 mm in diameter and provide for subsequent closure with high ease of use. Other needs identified include avoiding the vessel pinching associated with some closure techniques and the possible flow disturbances and restenosis associated with this, to leave nothing but suture behind in vessel at the end of the procedure to avoid flow disturbances, to provide high reliability of closure and to provide high predictability of closure.